Cross-Pollination for Granny Smith Apple Trees

"Granny Smith" apples have a green to yellow skin color and crisp flesh.

"Granny Smith" apple trees produce greenish-yellow skinned fruit with a crisp flesh, making them ideal for baking in pies and tarts. Like other types of self-fruitful apple trees, "Granny Smith" apple trees produce a better crop if cross-pollinated with a suitable apple tree variety. "Granny Smith" apple trees are hardy in U.S. Department of Agriculture plant hardiness zones 6 through 9 and bloom in mid-season.

"Granny Smith" Apples Are Self-Fruitful

Most apple tree varieties are self-fruitful, including "Granny Smith." Self-fruitful means that the tree has both male and female flowers and can adequately pollinate itself. However, even though "Granny Smith" is self-fruitful, growing compatible trees to pollinate the tree can help increase fruit yield and ensure well-developed fruit. While most varieties of apple trees can pollinate each other, some varieties make poor pollenizers because they produce sterile pollen. These poor pollenizers include "Jonagold," "Baldwin," "Winesap" and "Rhode Island Green."

Recommending Pollenizers for "Granny Smith"

To cross-pollinate apple tree varieties, you have to plant a compatible tree. "Snowdrift" crabapple is a useful pollenizer for apple trees that bloom mid- to late-season, like "Granny Smith." "Golden Delicious" is another smart choice because of its heavy pollen production. When choosing trees for cross-pollination, it is important that you choose apple varieties with overlapping bloom times because very early and very late varieties cannot pollinate each other.

The Pollination of Apple Trees

"Granny Smith" and other apple trees rely on bees, insects and even the wind for cross-pollination. The bees carry pollen from the male flowers to female flowers of neighboring trees. To ensure proper pollination, you need to plant apple trees within 40 to 50 feet of a compatible apple tree variety that blooms at the same time of year. If you only have room to plant a single tree, you can a hang a bucket of water from the tree and place fresh apple blossoms from a compatible tree in the bucket, or you can graft another apple variety onto the tree.

What Apple Trees Need

To ensure that apple trees flower so they can make or receive pollen, they need an area in full sun and should not planted where buildings or other trees can shade them. Most varieties of apples need winter chill. "Granny Smith" trees need 400 chill hours. If the trees do not achieve the required amount of chill hours, they may bloom too early, making them susceptible to frost or freeze damage. Insufficient chill hours year after year can kill trees.

About the Author

Based in Indiana, Molly Allman holds a B.A. in professional writing. She works as both a writer and author and enjoys writing articles on many different topics. She specializes in topics concerning health, crafts, family and lifestyles. Her fiction writing appears in "Bewildering Stories," "The Other Herald" and "Spectacular Speculations."